Air-pump for condensing-engines



(No Model.)

L. J. KNOWLES.

. AIR PUMP FOR GONDENSING ENGINES.

No. 246,857. Patented Sept. 6,1881.

Wiimesses. Iwven%or.

N. PETERS. PhnwLima n hm. Washinglon. D. C.

' NITED STATES PATENT OFFICE.

LUOIUS J. KNOWLES, OE WORCESTER, ASSIGNOR TO GEORGE F. BLAKEMANUFACTURING COMPANY, OF BOSTON, MASSACHUSETTS.

AIR-PUMP FOR CONDENSlNG-ENGINES.

SPECIFICATION forming part of Letters Patent No. 246,857, datedSeptember 6, 1881.

Application filed July 5, 1881. (No model.)

To all whom it may concern Be it known that I, LUOIUS J. KNOWLES, ofW'orcester, county of Worcester, State of Massachusetts, have inventedan Improvement in Air-Pumps for Condensing-Engines, of which thefollowing description, in connection with the accompanying drawing, is aspecification.

My invention relates to an air-pump for condensing steam-engines; and ithas for its object to improve the action of the pump, in order to obtainthereby a more efficient and uniform vacuum in the condenser.

In air-pumps as now commonly constructed the pressurein thepump-cylinderis not always sufficient-to open the delivery-valves,especially when first starting the pump. iVhen thepump is operating inthis manner the piston compresses the air or vapor or other gaseouscontents of the cylinder in front of it as ittravels through thecylinder, and it the pressure produced by this compression is notsufflciently great to open the delivery-valves, the gaseous contentswill merely expand again when the piston makesits return-stroke, and ifthe pressure in the condenser is not sufliciently great to open thesuction-valves leading to the cylinder, nothing will be added to itscontents, and the piston will merely travel back and forth, alternatelycompressing the contents of the cylinder and permitting them to expandwithout accomplishing any beneficial result. This operation, which mayoccur periodically while the pump is running, is chiefly due toexcessive clearance, and is obviated by this invention, which consistsin providing the cylinder with ports or passages leading to either endthereof and controlled by suitable valves operated by the attendant,through which any desired amount of water or other substantiallyinexpansible fluid may be admitted to the cylinder, preferably a triflein excess of the clearancespace, so that, as the said liquid issubstantially incompressible,the delivery-valves willbe positivelyopened at the end of the stroke of the piston, and in the return-strokea perfect vacuum will be formed to insure that the contents of thecylinder shall open the suction-valves.

The drawing represents, in vertical longitudinal section, an air-pumpprovided with my invention, illustrating several different arran gementsof the water-supplying ports or pipes and valves controlling them.

The pump-cylinder a, piston b therein, ports 0 0, leading to thesuction-valves d d, and de' livery-valves e e, the former controllingpassages leading to the inlet-chamherf, connected by the inlet-pipe gwith the condenser, and the latter controlling passages leading to thedischarge-chamber h, provided with a dischargepassage, i, may be of anyusual construction. The piston I) is shown as just beginning its strokein the direction of the arrow, and if it were pumping dry air or gaseousmaterial, and this were already considerably attenuated, it will be seenthatin completing its stroke in the direction of the arrow it merelycompresses the said contents from the aggregate volume of the cylinderto and port 0 to the volume of the latter alone, and this compressionmay not produce a suflicient pressure to open the valve 6, acted upon bythe pressure of the atmosphere, together with that of its closing-springand the liquid that remains in the chamber h and pipe or passage leadingtherefrom. If this were the case, the piston, in makingits returnstroke,would merely allow the contents of the cylinder to expand again, andtheir pressure would be no less than at the end of the preceding stroke,so that the suction-valve d would not again be opened, and the pumpwould continue operating in this manner without producing any usefuleffect until the pressure in the chamherf were increased sufficiently toopen the valve d. In order to obviate this, the cylinder a is providedwith a passage, preferably made as a port, Z, connecting the saidcylinder or the port 0 therefrom with a suitable supply of water orother liquid, preferably thatin the chamber h, the said port beingprovided with a valve, m, operated in any usual manner, as by thehand-wheel n, to properly control the passage of the liquid, so that anamount a trifle in excess of what is necessary to fill theclearance-space when the piston has completed its stroke may beadmitted, thus insuring the positive opening of the delivery-valves andan almost perfect vacuum in the cylinder and port 0 when the pistonmakes its return-stroke, thereby insuring the opening of thesuctionvalves and an eflicient vacuum in the chamber 5 f and condenser.

When this improvement is to be added to an air-pump already constructedon the common plan, the passage may consist, as shown at l, of pipesproperly connected with the chamber h and cylinder or port 0, as byscrewthreads, the said pipes being controlled by a "alve, m n, of anyusual or suitable construction.

When convenient and desirable, any other source of water than thechamber h may be employed, suitable passages, 1 controlled by the valve111, being shown in dotted lines as connected at either end of thecylinder a with a suitable supply of water or other liquid.

I claim- 1. In an air-pump for condensing-engines, the combination, withthe pump-cylinder, of

ports or passages connecting either end thereof with a supply of wateror other liquid, and controlling-valves therefor, whereby an amount ofwater suflicient to fill the clearance-space may be admitted to thecylinder, to cause the pump-valves to be positively opened,substantially as and for the purpose described.

2. The pump-cylinder and piston therein, combined with thedelivery-chamber and small ports connecting the said chamber with eachend of the cylinder, and adapted to remain open independently of theoperation of the piston and pump-valves, substantially as and for thepurpose described.

In testimony whereoflhave signed my name to this specification in thepresence of two subscribing witnesses.

LUGI'US J. KNOWLES.

Witnesses:

GEO. F. BLAKE, E. O. TURNER.

